Spray-gun control

ABSTRACT

A spray gun has a barrel for connection to a supply of pressurized air and a duct communicating with a reservoir for the material to be sprayed, a flow control valve being provided between the barrel and the duct and including a sleeve valve which, in a first end position determined by a return spring, opens the reservoir to atmosphere, and in a second position determined by pull on a trigger provides a flow of air from the barrel into the reservoir.

United States Patent Roche [4 1 July4, 1972 [54] SPRAY-GUN CONTROL 1,785,289 12/1930 Tucker ..137/625.68 1,066,263 7/1913 Von Dohn 1,982,045 11/1934 Clithero et al. ..l37/625.68 X

FOREIGN PATENTS OR APPLICATIONS 927,950 6/1963 Great Britain ..239/347 Primary Examiner-Robert B. Reeves Assistant Examiner-Frederick R. Handren Attorney-William Anthony Drucker [5 7] ABSTRACT A spray gun has a barrel for connection to a supply of pressurized air and a duct communicating with a reservoir for the material to be sprayed, a flow control valve being provided between the barrel and the duct and including a sleeve valve which, in a first end position determined by a return spring, opens the reservoir to atmosphere, and in a second position determined by pull on a trigger provides a flow of air from the barrel into the reservoir.

1 Claim, 3 Drawing Figures SPRAY-GUN CONTROL The object of the invention consists in the provision of an improved control device for paint and similar guns, making it possible at all times to ensure precise adjustment of pressures suited to all fluids.

It features the means used, taken either together or separately, and in particular the shunted mounting on the pressurized air intake of a cylinder connected to the container and fitted with apertures which are alternately closed or opened by a piston integral with the trigger and recalled by a spring which, like a slide-valve, conveys the pressurized air to the container for spraying and, to stop the feed, de-pressurizes the container at the same time as the pressurized air intake, which stops the paint from reaching the atomizer. This depressurization or pressurization is combined with an adjusting device positioned between the cylinder and the container and which, by means of a micro-metric needle, closes or opens an aperture with a larger diameter than the duct, making it possible to adjust the air pressure in the paint container without altering the volume of air distributed by the piston and the trigger;

In the attached drawings, given as a non-limiting example of one of the forms of construction of the invention:

FIG. 1 shows a longitudinal section of the device in the operating or container-pressurizing position.

FIG. 2 shows the spray gun with the controls in the off or container-depressurizing position.

FIG. 3 is a section showing constructional details of the pressure regulator.

The gun comprises a barrel 1 for the intake of air. A cylinder 2 is positioned on a parallel plane beneath it. The barrel 1 has an aperture 3 in it, communicating with the cylinder 2.

. The forward end of the cylinder 2 is connected to the container 5 by the duct 6 which goes through the water-tight cover 4.

The container 5 takes the plunger tube 7, going through the protective screen 9 which protects the air intake aperture 18.

Sliding inside the cylinder 2 there is a hollow tubular piston l0 open at both ends 11 and 12 in which a spring 13 is positioned, with the base stopper as its purchase point and the stop 14 as its mobile check point.

This piston comprises a top aperture 15 corresponding to the aperture 3, and a bottom aperture 20 corresponding to the second bottom aperture 21 in the cylinder 2.

The trigger 16 is integral with the piston 10.

The pressure-adjusting device is made up of a unit 22 FIG. 2 formed by the positioning on the duct 6 of a mounting 23 FIG. 3 comprising a threaded aperture 24 which takes a needle 25 with a micrometric control wheel 26 the shaped end 27 of which is designed gradually to block an aperture 28 leading from the surrounding atmosphere into the duct 6.

This opening 28 communicating with the surrounding atmosphere is larger in diameter than the duct 6.

The working of this device is thus evident.

When the pressurized air comes through the duct 1 and the trigger is pulled, the aperture 3 in the cylinder 2 coincides with the aperture 15 in the piston. The air then goes through 3, ll, 6 Arrow A and into the container 5. It causes the fluid to rise in the tube 7 and brings it to the spray nozzle 8.

Releasing the trigger 16 causes automatic recall by relaxing the spring 13 which thrusts against the stop 14 inside the ho]- low piston and carries the latter forward; it closes the aperture 3, opening the aperture 21 which coincides with the aperture 20.

The aperture 21 is then opened, which coincides with the aperture 20 Arrow B. The pressurized air contained in the container 5 escapes through 20, 21 Arrow 8 and de-pressurizes the fluid which is no longer fed to the spray nozzle.

Releasing the trigger stops the spray and pressing the trigger starts it.

However, pressure cannot be adjusted to intermediate strengths. There is either maximum pressure or a complete stoggage.

ustment is then made FIG. 3 by means of the wheel 26 which deflects part of the pressurized air through the duct 28.

When the duct 28 is closed, the whole of the pressure goes through the duct 6. According to the quantity of air which escapes through the aperture 28, there is greater or lesser pressure.

This device 22 FIG. 2 positioned between the pressurized air distribution to the container and the container itself, and combined with the device FIGS. 1 and 2, makes it possible to obtain maximum precision in the adjustment of the distribution pressure. The air generator still issues the same volume and only its pressure is altered by means of the outlet 28. Decrease from maximum pressure to complete de-pressurization, in view of the larger diameter of the aperture 28, is thus obtained immediately, which provides the user with constant adjustment, without having to bother about the movement of the trigger which, in its two positions, provides feed or stops pressure to the container.

Any kind of atornizing of more or less viscous fluids is made possible by a single initial adjustment, which can be altered for any kind of spray. This regulator also makes it possible to adjust the required pressure to correspond to that needed to spray the product. Moreover, pressure can be stopped by fully opening the aperture 28 FIG. 3.

By combining the controls, packings and packing-boxes are eliminated, as well as the control units which, when they come in contact with the product to be sprayed, get clogged and cause faulty working.

Nevertheless, the shapes, dimensions and positioning of the various units may vary within the limits of the equivalents, as may the materials used to make them, without thereby departing from the general concept of the invention just described.

lclaim:

l. A spray gun comprising a barrel for connection to a supply of pressurized air, a duct communicating with a reservoir for material to be sprayed, and a flow control valve connected between said' barrel and said duct, said flow control valve having a cylinder with one end closed and the other end open and communicating with said duct, said cylinder having in its wall a first intermediate aperture communicating with the barrel and a second axially-spaced aperture open to atmosphere, a hollow piston open at both ends and disposed in and longitudinally slidable in said cylinder between rest and actuated positions under the influence of a return spring, said piston having a first port which in the rest position of the piston is aligned with the second aperture of the cylinder thereby to provide a communication between the reservoir and atmosphere, said piston having a second port which in the actuated position of the piston is aligned with the first aperture of the cylinder thereby to provide a communication between the barrel and the reservoir and an air pressure control device in said duct which maintains a constant volume of air supply at infinitely variable pressure by the axial displacement of a needle valve in an opening between said duct and the atmosphere wherein said opening is larger in diameter than the inside diameter of said duct.

i i I. 

1. A spray gun comprising a barrel for connection to a supply of pressurized air, a duct communicating with a reservoir for material to be sprayed, and a flow control valve connected between said barrel and said duct, said flow control valve having a cylinder with one end closed and the other end open and communicating with said duct, said cylinder having in its wall a first intermediate aperture communicating with the barrel and a second axially-spaced aperture open to atmosphere, a hollow piston open at both ends and disposed in and longitudinally slidable in said cylinder between rest and actuated positions under the influence of a return spring, said piston having a first port which in the rest position of the piston is aligned with the second aperture of the cylinder thereby to provide a communication between the reservoir and atmosphere, said piston having a second port which in the actuated position of the piston is aligned with the first aperture of the cylinder thereby to provide a communication between the barrel and the reservoir and an air pressure control device in said duct which maintains a constant volume of air supply at infiniTely variable pressure by the axial displacement of a needle valve in an opening between said duct and the atmosphere wherein said opening is larger in diameter than the inside diameter of said duct. 